Electric furnace



C. l. HAYES.

ELECTRIC FURNACE.

APPLICATION FILED MAR. 2, 1921.

Patented Sept. 19, 1922.

T all whom it may] concern: a

tensity of t Patented Sept. 19, 1922.

UNITED STATES PATENT OFFICE.

CARL I. HAYES, Oil? EDGEWOOD, RHODE ISLAND.

ELECTRIC summon.

Application filed March 2, 1921. Serial No. 448,965.

Be it known that I, CARL I. HAYES, a citizen of the United States, residing at Edgewood, in the county of Providence and State of Rhode Island, have invented certain new and useful Improvements in Electric Furnaces, of which the following is a specification.

This invention relates to an improved construction of electric furnace or oven more particularly adapted for heat treating of metals such as annealing, hardening or tempering, or the same may be used for baking and enameling metal such as jewelry, or

for baking japanned or varnished objects and the primary object of this invention is to provide a current-controlling device in the heating circuit and means for thermally controlling the action of said device by the temperature in the heat-treating chamber.

A further object of the invention is the provision of a fusible element supported within the heating zone and connecting this element to the current controlling device in such a way that the fusing of this element causes the controlling device to affect the volume of the heating current.

With these and other objects in view, the invention consists of certain novel features of construction, as will be more fully described, and particularly pointed out in the appended claims.

In the accompanying drawing:

Fi re 1 is a sectional side elevation of one orm of oven or furnace; also showing one form of switch or current controlling device inserted into the heated circuit whereby the volume of the current may be automatically'. re lated or controlled by'the inib heat in the work-treating chamber.

Figure 2 is a detailed 'top view of the thermal-controlling element.

In practice while furnaces of this character are in operation they are practically noiseless and there is nothing about them to indicate that the heat-generating current is on and there is'therefore a great tendency of the attendant, who may at the same time be running other machines, to forget that the heat is on, in which case if it is left too long extensive damage may be done and in some cases the heating unit is destroyed.

As is well known by those accustomed to the operation of such furnaces, sufficient current must be first applied to the furnace to raise the temperature of the worktreating chamber together with the work deposited inthe chamber to the required temperature within a reasonable time and after this chamber has been heated to ether with the work therein, the full num er of heat units are no longer required by the surrounding parts and the temperature rises very rapidly and therefore the current must be reduced to prevent over-heating of the furnace and the work. Therefore to avoid this difliculty of over-heating I have provided a simple attachment for the furnace which automatically shuts off or reduces the heating current thus preventing in'ury to the furnace and the work, and the following is a detailed description of one means by which this result may be accomplished With reference to the drawing, 10 designates the body portion ofa furnace, which plied with current through the wires 14 and 15.

To this oven or furnace I have applied a thermal current control which comprises essentially a tube 16 of suitable relatively non-fusing material, the inner end of which extends through the rear wall 17 of the furnace or oven into the heat zone or chamber, preferably a substantial distance beyond the rear wall 18 thereof and this tube may be held in position in the chamber wall by any suitable means such for instance as a set screw 19 whereby the tube may be readily removed when desired. .On the inner end of this tube is held a fusible element 20 such as a glass bead, or other suitablefusible device. To this fusible element I have attached a non-fusing wire 21 which leads out through the tube and its outer end is connected to a member 31 which under tension of sprin 26 presses against the arm 22' of a knife filade switch, the lower end of this switch being pivoted at 23 on the bracket 24: whileits upper end is held by friction in engagement with the spring clip or contact 25 whereby when the head 20 fuses this connector member is released and this arm 22 under action of the compressed spring 26 and the coil spring 27 moves outward to break the connection at the point 25' thus causing the current, instead of passing through the blade of switch 22, to pass through the resistance coil 28 thus reducing the volume of the current and so the heat applied to the work heatin chamber.

.n order to reset the evice after the fusible bead or element has been melted and the switch forced out, it is only necessary to loosen the screw 19 slide out the tube, connect another bead to the wire and position it on the inner end of the tube then replace the whole in operative position to retain the switch blade in its contact '25 after which the work is again inserted into the chamber 11 and the door 30 closed to repeat the heat treating operation above described. V

The device is extremel simple and practical in construction and by its use a current may be automatically controlled to the heated work-treating chamber to prevent over heating and damaging the furnace and the work contained therein.

-mechanica I do not wish to'be restricted to the form of switch shown as any current-controlling device may be inserted into the circuit to be automatically operated by a thermal inset in the heat-treating zone.

The foregoing description is directed solel towards the construction illustrated but desire it to be understood that I reserve the 1privilege of resorting to all the changes to which the device is susceptible, the invention being defined and limited only by the termsof the appended claims/ I I claim:

, 1. In a device of the character described, an electrically-heated work-treating chamber, a fusible element located in said chamber, a current controlling device in the heatber and means whereby the fusing of said element within said chamber is caused to permit the operation of said device to affect the heating current.

2. In a device of the character described, an electrically-heated work treating chamber, a fusible element su ported in said chamber, .a current controlling device in the heating circuit located externally of said chamber and a non-fusing element connecting said fusible elementwith said controlling device to hold the latter out of operative position until the former is fused.

3. In a device of the character described, an electrically-heated work treating chamber, a non-fusing support extending a substantial distance into said chamber beyond the wall thereof, a fusible element on said support positioned in a highly heated portion of said chamber, a current-controlling device in the heating circuit located externally of said chamber, and a non-fusing connector between said element and said device arranged to release the latter when the element is fused to affect the heating current.

4. In a device of the character described, an electrically heated work treating chamber, a non-fusing tube extending a substantial distance inward into said chamber from the wall thereof, an electric heating circuit, an automatically actuated switch in said circuit, a fusible element supported on the end of said tube, a connector between said element and-said switch whereby when said element is fused said connector permits said switch to be moved to change the volume of the heating current upon said chamber.

In testimony whereof I aflix my signature.

CARL I. HAYES.

ing circuit, located externally of said cham- 

